1. Field of the Invention
This invention relates to a process for the preparation of coated magnetic polymer particles.
2. Description of the Related Art
Magnetic polymer particles are of general utility in various medical and biochemical fields, for example as transport vehicles for the delivery of pharmaceutical products, for diagnostic purposes, for separation and for synthetic purposes. Such particles rely upon their magnetic properties in order to perform these functions. In diagnostic assay applications, for example, application of a magnetic field to a sample containing an analyte bound to magnetic polymer particles allows the isolation of the analyte without the use of centrifugation or filtration and in therapeutic applications, for example, application of a magnetic field to the patient may serve to target drug-carrying magnetic polymer particles to a desired body site.
By magnetic is meant herein that the polymer particles contain superparamagnetic crystals. Thus the magnetic polymer particles are magnetically displaceable but are not permanently magnetizable. Many processes for preparing magnetic polymer particles are known, a large number of which involve preparing maghemite- or magnetite-containing polymer particles from pre-formed magnetic iron oxides, e.g. magnetite. Some of processes involved are described in U.S. Pat. No. 4,654,267 (Ugelstad) the contents of which are incorporated herein by reference.
With the development of devices which can measure very small changes in magnetism as well as the growth in nanotechnology it is envisaged that magnetic particle users will desire smaller particles with which to conduct their assays etc in the future. Moreover, the magnetic particles will need to be manipulated to carry reactive groups which can be readily coupled with labels to provide an ideal solid phase for biochemical procedures.